Mycosis fungoides (MF) is a cutaneous T-cell lymphoma characterized in its early stages by a superficial band-like infiltrate with epidermotropism of lymphocytes without particularly atypical cytologic features. Even though clinicopathologic presentation is diagnostic in typical cases, some inflammatory skin disorders can simulate the histopathologic features of early MF. In this study we present data on 9 patients affected by lichen sclerosus (LS) (M:F ratio 8:1; age range 7–75 years; mean age 31.3 years; median age 13 years), who presented with histopathologic features simulating early lesions of MF. The histopathologic picture was characterized in all cases by a dense, band-like infiltrate of lymphocytes within the superficial dermis, with exocytosis of lymphocytes within the lower part of the epidermis. The papillary dermis was expanded and showed focally coarse bundles of collagen simulating MF. The typical signs of LS were either absent or present only focally. Molecular analyses of the TCRγ gene rearrangement performed with the polymerase chain reaction (PCR) technique revealed a polyclonal smear in eight cases, and a monoclonal band in one. Our study shows that LS can present with histopathologic features simulating early MF. Especially in cases revealing a monoclonal population of T lymphocytes by PCR, the correct diagnosis may be overlooked without proper clinical information and clinicopathologic correlation. Lichen sclerosus should be added to the list of cutaneous T-cell pseudolymphomas.
Mycosis fungoides (MF) is characterized histologically in its early stages by a patchy lichenoid lymphohistiocytic infiltrate in the papillary dermis with epidermotropism of lymphocytes. Although this pattern is typical of MF, some inflammatory diseases may display similar histopathological changes, and differentiation of MF from these simulators is one of the most vexing problems in dermatopathology. 1,2 The best known among these benign cutaneous diseases are actinic reticuloid, 3–5 lymphomatoid contact dermatitis, 2,6 lymphomatoid drug eruption, T-cell type, 7,8 and lymphomatoid keratosis. 9,10
We report on 9 patients with lichen sclerosus (LS) showing histopathologic features simulating early MF.
From the Department of Dermatology (Drs Citarella, Massone, Kerl, and Cerroni), University of Graz, Austria; Department of Dermatology (Dr Citarella), University of Rome “Tor Vergata”, Italy; and DiSEM, Section of Dermatology (Dr Massone), University of Genoa, Italy.
Reprints: Lorenzo Cerroni, MD, Department of Dermatology, University of Graz, Auenbruggerplatz, 8 A-8036 Graz, Austria (e-mail: lorenzo.cerroni@kfunigraz.ac.at).
